Build a browser answer view and local event stream for developers integrating assistant output. Handle split UTF-8 bytes, event IDs, reconnection, cancellation and partial citations. Preserve the difference between an interrupted draft and a completed answer, with a downloadable event trace to reproduce rendering failures.
Standard libraries only. Four stages, approximately eight hours. TypeScript, Go implementations are exercised by the grader.
Build it
- Decode chunked bytes into complete events
- Render text and citations by stable identity
- Handle reconnect and cancellation
- Export and replay an interrupted-answer trace
python3 scripts/project_test.py streaming-answer-recovery --init /tmp/streaming-answer-recovery-work
python3 scripts/project_test.py streaming-answer-recovery --stage 1 --path /tmp/streaming-answer-recovery-work --strict
python3 scripts/project_test.py streaming-answer-recovery --all --solution --strictThe fresh starter fails until you implement it. Reference-solution runs never grant learner completion certificates.
Run the actual interrupted stream
cd projects/streaming-answer-recovery/solution
python3 demo.py
node --experimental-strip-types build-browser.ts /tmp/stream-browserThe demo builds the Go fixture, starts a finite loopback server, reads its URL and runs the TypeScript client twice. First output is interrupted Caf at event 1. Resume sends Last-Event-ID:1 and completes Café without duplicated text. The accepted-event trace is written to /tmp/aiefs-answer-trace.json and replayed by the actual state reducer.
For your own SSE endpoint: node --experimental-strip-types cli.ts URL /tmp/trace.json. The CLI makes at most two connections. For browser integration, import mount from the generated answer.js and mount it with a same-origin SSE URL, or configure CORS on your own server. For a complete local browser run, use go run . --listen 127.0.0.1:8137 --seconds 120 --web /tmp/stream-browser and open localhost:8137. The Go fixture serves the generated page and /events on one origin; it does not grant cross-origin access. The finite server exits after the requested lifetime.
The SSE parser supports UTF-8, CR/LF framing, comments, data fields, event type and persistent last ID. It ignores retry fields; reconnect policy belongs to the caller. The authored answer protocol requires contiguous positive numeric event IDs and payload type text/citation/complete. This is a teaching protocol, not an adapter for any specific LLM provider.
Trace schema version 1 contains accepted events and status. It reproduces rendering state, including interrupted or cancelled answers; it does not retain partial transport bytes. Status completed requires an explicit complete event. WHATWG SSE defines framing and resume fields.
Completion evidence
python3 scripts/project_test.py streaming-answer-recovery --all --path /tmp/streaming-answer-recovery-work --strict --report /tmp/streaming-answer-recovery-result.jsonLocal reports are unsigned, self-reported evidence. The editable figures calculate illustrative values; the CLI runs the actual implementation.
